// Copyright (c) 2013 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef MEDIA_MIDI_MIDI_MANAGER_H_
#define MEDIA_MIDI_MIDI_MANAGER_H_

#include <stddef.h>
#include <stdint.h>

#include <set>
#include <vector>

#include "base/macros.h"
#include "base/memory/ref_counted.h"
#include "base/synchronization/lock.h"
#include "base/time/time.h"
#include "media/midi/midi_export.h"
#include "media/midi/midi_port_info.h"
#include "media/midi/midi_service.mojom.h"

namespace base {
class SingleThreadTaskRunner;
} // namespace base

namespace midi {

// A MidiManagerClient registers with the MidiManager to receive MIDI data.
// See MidiManager::RequestAccess() and MidiManager::ReleaseAccess()
// for details.
// TODO(toyoshim): Consider to have a MidiServiceClient interface.
class MIDI_EXPORT MidiManagerClient {
public:
    virtual ~MidiManagerClient() { }

    // AddInputPort() and AddOutputPort() are called before CompleteStartSession()
    // is called to notify existing MIDI ports, and also called after that to
    // notify new MIDI ports are added.
    virtual void AddInputPort(const MidiPortInfo& info) = 0;
    virtual void AddOutputPort(const MidiPortInfo& info) = 0;

    // SetInputPortState() and SetOutputPortState() are called to notify a known
    // device gets disconnected, or connected again.
    virtual void SetInputPortState(uint32_t port_index,
        mojom::PortState state)
        = 0;
    virtual void SetOutputPortState(uint32_t port_index,
        mojom::PortState state)
        = 0;

    // CompleteStartSession() is called when platform dependent preparation is
    // finished.
    virtual void CompleteStartSession(mojom::Result result) = 0;

    // ReceiveMidiData() is called when MIDI data has been received from the
    // MIDI system.
    // |port_index| represents the specific input port from input_ports().
    // |data| represents a series of bytes encoding one or more MIDI messages.
    // |length| is the number of bytes in |data|.
    // |timestamp| is the time the data was received, in seconds.
    virtual void ReceiveMidiData(uint32_t port_index,
        const uint8_t* data,
        size_t length,
        double timestamp)
        = 0;

    // AccumulateMidiBytesSent() is called to acknowledge when bytes have
    // successfully been sent to the hardware.
    // This happens as a result of the client having previously called
    // MidiManager::DispatchSendMidiData().
    virtual void AccumulateMidiBytesSent(size_t n) = 0;

    // Detach() is called when MidiManager is going to shutdown immediately.
    // Client should not touch MidiManager instance after Detach() is called.
    virtual void Detach() = 0;
};

// Manages access to all MIDI hardware.
class MIDI_EXPORT MidiManager {
public:
    static const size_t kMaxPendingClientCount = 128;

    MidiManager();
    virtual ~MidiManager();

    // The constructor and the destructor will be called on the CrBrowserMain
    // thread.
    static MidiManager* Create();

    // Called on the CrBrowserMain thread to notify the Chrome_IOThread will stop
    // and the instance will be destructed on the CrBrowserMain thread soon.
    void Shutdown();

    // A client calls StartSession() to receive and send MIDI data.
    // If the session is ready to start, the MIDI system is lazily initialized
    // and the client is registered to receive MIDI data.
    // CompleteStartSession() is called with mojom::Result::OK if the session is
    // started. Otherwise CompleteStartSession() is called with a proper
    // mojom::Result code.
    // StartSession() and EndSession() can be called on the Chrome_IOThread.
    // CompleteStartSession() will be invoked on the same Chrome_IOThread.
    void StartSession(MidiManagerClient* client);

    // A client calls EndSession() to stop receiving MIDI data.
    void EndSession(MidiManagerClient* client);

    // Invoke AccumulateMidiBytesSent() for |client| safely. If the session was
    // already closed, do nothing.
    void AccumulateMidiBytesSent(MidiManagerClient* client, size_t n);

    // DispatchSendMidiData() is called when MIDI data should be sent to the MIDI
    // system.
    // This method is supposed to return immediately and should not block.
    // |port_index| represents the specific output port from output_ports().
    // |data| represents a series of bytes encoding one or more MIDI messages.
    // |length| is the number of bytes in |data|.
    // |timestamp| is the time to send the data, in seconds. A value of 0
    // means send "now" or as soon as possible.
    // The default implementation is for unsupported platforms.
    virtual void DispatchSendMidiData(MidiManagerClient* client,
        uint32_t port_index,
        const std::vector<uint8_t>& data,
        double timestamp);

protected:
    friend class MidiManagerUsb;

    // Initializes the platform dependent MIDI system. MidiManager class has a
    // default implementation that synchronously calls CompleteInitialization()
    // with mojom::Result::NOT_SUPPORTED on the caller thread. A derived class for
    // a specific platform should override this method correctly.
    // This method is called on Chrome_IOThread thread inside StartSession().
    // Platform dependent initialization can be processed synchronously or
    // asynchronously. When the initialization is completed,
    // CompleteInitialization() should be called with |result|.
    // |result| should be mojom::Result::OK on success, otherwise a proper
    // mojom::Result.
    virtual void StartInitialization();

    // Finalizes the platform dependent MIDI system. Called on Chrome_IOThread
    // thread and the thread will stop immediately after this call.
    // Platform dependent resources that were allocated on the Chrome_IOThread
    // should be disposed inside this method.
    virtual void Finalize() { }

    // Called from a platform dependent implementation of StartInitialization().
    // It invokes CompleteInitializationInternal() on the thread that calls
    // StartSession() and distributes |result| to MIDIManagerClient objects in
    // |pending_clients_|.
    void CompleteInitialization(mojom::Result result);

    void AddInputPort(const MidiPortInfo& info);
    void AddOutputPort(const MidiPortInfo& info);
    void SetInputPortState(uint32_t port_index, mojom::PortState state);
    void SetOutputPortState(uint32_t port_index, mojom::PortState state);

    // Dispatches to all clients.
    // TODO(toyoshim): Fix the mac implementation to use
    // |ReceiveMidiData(..., base::TimeTicks)|.
    void ReceiveMidiData(uint32_t port_index,
        const uint8_t* data,
        size_t length,
        double timestamp);

    void ReceiveMidiData(uint32_t port_index,
        const uint8_t* data,
        size_t length,
        base::TimeTicks time)
    {
        ReceiveMidiData(port_index, data, length,
            (time - base::TimeTicks()).InSecondsF());
    }

    size_t clients_size_for_testing() const { return clients_.size(); }
    size_t pending_clients_size_for_testing() const
    {
        return pending_clients_.size();
    }

    const MidiPortInfoList& input_ports() const { return input_ports_; }
    const MidiPortInfoList& output_ports() const { return output_ports_; }

private:
    enum class InitializationState {
        NOT_STARTED,
        STARTED,
        COMPLETED,
    };

    void CompleteInitializationInternal(mojom::Result result);
    void AddInitialPorts(MidiManagerClient* client);
    void ShutdownOnSessionThread();

    // Keeps track of all clients who wish to receive MIDI data.
    typedef std::set<MidiManagerClient*> ClientSet;
    ClientSet clients_;

    // Keeps track of all clients who are waiting for CompleteStartSession().
    ClientSet pending_clients_;

    // Keeps a SingleThreadTaskRunner of the thread that calls StartSession in
    // order to invoke CompleteStartSession() on the thread.
    scoped_refptr<base::SingleThreadTaskRunner> session_thread_runner_;

    // Tracks platform dependent initialization state.
    InitializationState initialization_state_;

    // Keeps false until Finalize() is called.
    bool finalized_;

    // Keeps the platform dependent initialization result if initialization is
    // completed. Otherwise keeps mojom::Result::NOT_INITIALIZED.
    mojom::Result result_;

    // Keeps all MidiPortInfo.
    MidiPortInfoList input_ports_;
    MidiPortInfoList output_ports_;

    // Protects access to |clients_|, |pending_clients_|,
    // |session_thread_runner_|, |initialization_state_|, |finalize_|, |result_|,
    // |input_ports_| and |output_ports_|.
    base::Lock lock_;

    DISALLOW_COPY_AND_ASSIGN(MidiManager);
};

} // namespace midi

#endif // MEDIA_MIDI_MIDI_MANAGER_H_
